Dry cell



Feb. ll, 1941. c. F. BUGESS DRY CELL Filed Sept. 25, 1936 ggf/2%?? Patented-Feb. 1,1, 1941 par om omnes r. Burgen, nekeeue, miglior. by -mesne allisnmenfl. to Burgos! Battery pony, Ultimo, lll n corporation of j Application september es, 193e, serial No. 1025er 1 claim. l(ci. 13s- 127)v This inventionrelates"toa dry cell of the Le' Clanche type in which 'the zinc electrode consists of a multiplicity of layers-oi zinc.

It is an obiect'of this invention .to provide a dry 5 cell having improved characterlstics over those of a dry cell employing' an electrode comprising a single layer o! mno. It is a further object oi the invention to provide means for protecting a dry cell against exdl0 cessive initial voltages and against local action.

This invention is illustrated in the accompanyins drawing in which:

into a cylindrical tube:

Fis. 1 u a sectiensi view er strip er une roues.

l5 Fig. 2 is a view, partly in section, of e cylindre' cal dry cell employing a zinc tube such lasis l1- lustrated in Fig. l; A

Fig. 3 is an enlarged fragmental sectional view ofthedrycellofhlg.2;`

to rieusaviemparuyinseeuemoradmerent' My invention is applicable especially to the production of the cylindrical type of zinc dry cell can, although it may -be applied to the production of the electrodes of other forms of dry cells such as those of the hat or plate tym. The can, or

other form of electrode, is made by sum1-impe a number oi* layersof thin zinc sheets or mno foil, the several sheets erably being attached d@ to each other by m :1

described hereinafter. A cylindrical can is made by ro a thin sheet of zinc on a cylindrical core or am until a tube of the desired wall thlcess is obtains-dond then applying a bot tom closure member to one end oi' the tube. The

depo i f mix, electrolyte paste, carbon rod Y and seal are then introduced into the can in the usual way. l

In the embodiment of this invention shown in Figs. l and2, athlnzincsheet orioil itisrolled upon itself to form a tube, the walls of which are thus e to t loie. multiplicity of layers of zinc. While only three layers are shown. this f lacquercement, ora thermo plastic r l is on heating and cooling forms a tight and water-7` of a. suitable esive as prooi joint. The end of the tube is'closed by a zinc cap I3 which may be angedas shown sons to iit tightly upon the end ofthe tube. The joint is made water-tight bysoldex-or resin or any other suitablematerial. As an alternative, the 5 end capi) may be of paper or other suitable xinaterial. coated with parailln or other water and zinc. chloride resisting substance, or it may be composed of a fusible sealing compound such as is usually used for the top closures of cells.. After lo the can. is thus formed, .the active ingredients. such as .the depolarizing core Il, the carbon eleci trode :iLthe electrolyte paste Il, the top washer il and the top closure Il,are inserted in the usual way anda tube il of paper or other elec 15 trical insulating material-may be fitted over the zinc tube. The paper tube I9 extends above the top ofthe zinc tube and the top seal covers the end oi.' the' zinc tube as shown.

Ii a bottom closure of zinc is used a layer 0F20 paper or other electrical insulating material 20, impregnated with parallln or other suitable water and zinc chloride resisting substance, is interposed betweenthe bottomend closure and the bottom oi' the depolarizing core. A 25 In the preferred embodiment of this invention a illmof thermoplastic resin is arranged between the superimposed layers of zinc. The resin is applied to a portion of the surface of the zinc sheet such that when the sheet is rolled into an 30 approximately cylindrical tube, the lm of thermoplastic resin lies between the entire supe areas oi the successive layers of :une and leaves exposed the interior surface of the tube. l'lpon Y A applying heat such that the resin becomes plas' 35 tic and sticky, and then cooling, the layers of zinc adhere and form a rigid, watertient l l The layers are separated from one another by the nlm of resin, and this separation provides important advantages as will be pointed 4o A polymerized vinyl acetate resin is the pre- 45 ferred material. It is a thermoplastic, adhesive resin, which is normally non-conductive. However. a thin ilm of this substance, when .exposed to the electrolyte is slightly permeable to the electrolyte solution and when the external ch'- 5o cuit is closed, the 111m becomes dissolved, dis-V integrated, decomposed or otherwise aii'eoted so that it permits the ready Vilotv ot current. 'Inecharacter ot the action by the electrolyte is'not imaerstood but the l111m is erected 1n such s wey sr that suiiicient current is permitted to now to render the cell operative for all types of service. 'Ihe resin is applied by making a dilute solution thereof in a suitable solvent, such as acetone, and applying the `solution to the zinc surface. The solvent evaporates; leaving the thermoplastic resin coating ori-the zinc. The adhesive separating layer is shown at 2l lin Fig. 3.

Other materials than thermoplastic resin may be used between the superimposed layers of zinc. 'I'he material should be of such composition that it is permeable to the electrolyte, or is dissolved by the electrolyte or otherwise ailected, to aiord access of the electrolyte to the succeeding layers that the galvanic action of the battery is notl affected by the 'of zinc as the dry'cell becomes discharged. The action -should occur with suicient promptness so interfered with by the separating material. Other suitable adhesives are hide glue and boiled starch adhesive. Regenerated cellulose may be used and other materials having a cellulose base, or containing cellulosic ingredients. terials are destroyedby strong zinc chloride solutions.

The local couples which develop in dry cells having the ordinary soldered, extruded or drawn zinc cans are largely eliminated by the use of my improved multiple-laver can. This is because the strains and other non-uniformities, which are commonly caused by the forming operations and the use of hot solder are avoided. In addition, any non-uniformities which may be present do not extend through the entire thickness of the can wallbut` only through the thickness of one layer., As a result, dry cells .employing the multiple layer electrodes of this invention are relacan by local action. The properties of the battery and especially the storage or shelf" life, are improved as a consequence. -placed into action by the delivery of current, the inner layer of zinc is attacked rst and-is corroded until it is substantially consumed. The adjacent layer of separating material is then exposed and is dissolved, decomposed, or otherwise electrolyte, as described heretofore.

During the electrolytic corrosion of the inner zinc layer, a quantity of zinc chloride is formed at the surface of the zinc layer and goes into solution in the aqueous electrolyte. The separating materials, which are. permeable to zinc chloride solution, are softened and made more conductive by such solution when they become exposed thereto. All of the adhesive separating materials described herein are affected by the electrolyte in the presence of electrolytic action in such a way that the succeeding layers of zinc are progressively made accessible to the electrolyte and-the galvanic action of the dry cell proceeds in a reguvlar and uniform manner until the layers of zinc are substantially consumed. Any local action :clean zincsurface. The mercury is applied only where it is needed, resulting in en emcient and economical use of the mercury, which, under ordinary methods. of construction, is distributed throughout the entire thickness oi' the sinccan.`

Buch ma- When the cell is The described multiple layer construction prevents the mercury from getting upon the outer layer or layers of zinc, and a relatively large proportion of mercury to zinc may be used without encountering the structural weakness whichresuits when the ordinary zinc can is amalgamated with relatively large amounts of mercury.

In a further embodiment of the invention the adhesive separating material may be applied to the entire surface of the zinc sheet whereby a nim of the material isprovided upon the interior surface ofthe zinc tube. The film, being permeable to the electrolyte to a restricted degree, permits only a slow diiusion of ions therethrough during the storage period, with the result that the local v of current, a reaction takes place upon the film,

which, as described heretofore, affects the iilm in lsuch a manner as to permit sufficient current to now to render the cell operative.

The voltage of a new dry cell is relatively high when it is initially placed in use. The lamps of flashlights sometimes burn out during this initial high-voltage period. The protective interior coating described heretofore prevents the high current caused by the high initial voltage. In fact, the initial current may be slightly lower than the normal. It reaches normal, however, after a short period ,of use. `'Ihe protective coating of this invention has the advantage that it is affected so as to permit the flow of current by the action of the drycell which takes place when the dry cell is placed in use. This insures that the protection will continue throughout the storage period. This interior protective coating may be applied to any type of dry cell can and is not limited to a multiple layer can.

The multiple layer zinc tube of this invention may be used for making a double-ended dry cell.

Such a dry cell is illustrated in Fig. 4. A suitable separator 22 may be inserted across the Imiddle of a relatively long multiple layer zinc Fig. 5. The sheet of zinc is represented by the rectangle abcd. Portion abef is coated with the adhesive separating material and the area fecdis amalgamated. A cut or slot ah is made in the end portion as shown, and the strip abba is l turned upward to b'h. to constitute a conductive lead 3| for connecting the cell to another cell or to a cooperating external circuit. The zinc sheet 3l is then rolled around a mandril in such a manner that the areafecd constitutes the inner exposed surface of the resulting tube and the terminal lead Il is connected to the outer layer of zinc. The layers may then be. united by a process suitable'for the type of adhesive employed. The terminal lead may also be formed as illustrated in Fig. 6 by severing the zinc sheet 32 along the lines kmn in the side marginal portion thereofl the partially severed strip 38 being turned back as shown in dotted lines.

Advantages of this construction. in addition to those mentioned heretofore, are lthat the perromance characteristics are more uniform throughout the life of the battery, the zincot the zinc can is used emciently and is consumed completely in the production of electric was?. a

purer and softer grade of zinc may be employed ins of the cans, no scrap zinc being Produced as in the drawing of zinc cups.' It also is obvious that this type of construction lends itself well to the production oi.' tubes of circular, square, rectangular, oval or other form. and or any desired length.

I claim:

In a dry cell, a zinc electrode having a surface thereof exposed to the electrolyte. and a coating 

